Notes: Only two prototypes
were completed before the end of the war. Used a five-cylinder swashplate
engine.

.

45
cm (17.7") Torpedoes

.

45 cm (17.7") Type 91
(1931) Mod 1

.

Ship Class Used On

Aircraft

Date Of Design

1931

Date In Service

1933

Weight

1,728 lbs. (784 kg)

Overall Length

208 in (5.275 m)

Negative Buoyancy

227 lbs. (103 kg)

Explosive Charge

331 lbs. (150 kg) Type 97

Power / Range / Speed

140 HP / 2,200 yards (2,000 m) / 41-43
knots

Propulsion

Kerosene-air wet-heater

Wander Left or Right (max)

N/A

Notes: This was a pre-war
torpedo although still in service ten years later. "Nell" (G3M) torpedo
bombers carried this weapon against the HMS Prince of Wales and HMS Repulse
on 10 December 1941.

.

45 cm (17.7") Type 91
(1931) Mod 2

.

Ship Class Used On

Aircraft

Date Of Design

1940

Date In Service

1941

Weight

1,841 lbs. (935 kg)

Overall Length

216 in (5.486 m)

Negative Buoyancy

271 lbs. (123 kg)

Explosive Charge

452 lbs. (205 kg) Type 97

Power / Range / Speed

140 HP / 2,200 yards (2,000 m) / 41-43
knots

Propulsion

Kerosene-air wet-heater

Wander Left or Right (max)

N/A

Notes: Compared to Mod
1, Mod 2 had a heavier explosive charge, a thinner air vessel and anti-roll
stabilizers. It was first delivered in April 1941 and was carried
into action by "Betty" (G4M) bombers against the Prince of Wales and Repulse.
A version of this torpedo heavily modified for use in shallow waters was
carried by "Kate" (B5N) attack planes at Pearl Harbor.

.

45 cm (17.7") Type 91
(1931) Mod 3

.

Ship Class Used On

Aircraft

Date Of Design

1941

Date In Service

1942

Weight

1,872 lbs. (849 kg)

Overall Length

216 in (5.486 m)

Negative Buoyancy

379 lbs. (172 kg)

Explosive Charge

529 lbs. (240 kg) Type 97

Power / Range / Speed

140 HP / 2,200 yards (2,000 m) / 41-43
knots

Propulsion

Kerosene-air wet-heater

Wander Left or Right (max)

N/A

Notes: Compared to Mod
2, Mod 3 had a heavier explosive charge, the air vessel was thickened for
a heavier charge. Bronze parts were substituted for steel where possible
and eight tail fins were experimented with in some units.

Notes: Compared to Mod
3, Mod 3 Improved had a heavier explosive charge, the top side of the afterbody
and engine room strengthened with longitudinal T bars to permit 300 knot
launching speed. This was followed in 1944 by the Mod 3 Strong which
had I instead of T bars for strengthening the top side of the afterbody
and also the underside of the warhead nose, the air vessel was thinned
with reduced pressure and range. These modifications allowed a 350
knot launching speed. Mod 4 was the same torpedo with a heavier explosive
charge. Mod 7 Strong had a longer, heavier warhead.

.

45 cm (17.7") Type 94
(1934) Mod 2

.

Ship Class Used On

Aircraft

Date Of Design

1934

Date In Service

Not in service

Weight

1,870 lbs. (848 kg)

Overall Length

208 in (5.283 m)

Negative Buoyancy

N/A

Explosive Charge

331 lbs. (150 kg) Type 97

Power / Range / Speed

N/A / 3,300 yards (3,000 m) (?) / 48 knots
(?)

Propulsion

Kerosene-air wet-heater

Wander Left or Right (max)

N/A

Notes: A limited number
of these torpedoes were made but they do not appear to have entered service
use. Powered by a dual-row, eight cylinder radial engine with poppet
valves.

.

45 cm (17.7") Type 97
(1937)

.

Ship Class Used On

Midget Submarines

Date Of Design

1937

Date In Service

1939

Weight

2,161 lbs. (980 kg)

Overall Length

220 in (5.600 m)

Negative Buoyancy

553 lbs. (251 kg)

Explosive Charge

772 lbs. (350 kg) Type 97

Power / Range / Speed

205 HP / 6,000 yards (5,500 m) / 44-46
knots

Propulsion

Kerosene-oxygen wet-heater

Wander Left or Right (max)

90 yards @ 6,000 yards (80 m @ 5,500 m)

Notes: Designed for
Midget Submarines and was essentially a smaller version of the Type 93
and Type 95 torpedoes. Only about 100 were made as similar problems
with the first air vessel were found. Used operationally only during
the Pearl Harbor attack.

.

45 cm (17.7") Type 98
(1938)

.

Type 98 Torpedo on the beach at Sydney,
AustraliaAustralian War Memorial photograph 305024

Ship Class Used On

Midget Submarines

Date Of Design

1941

Date In Service

1942

Weight

2,094 lbs. (950 kg)

Overall Length

220 in (5.600 m)

Negative Buoyancy

487 lbs. (221 kg)

Explosive Charge

772 lbs. (350 kg) Type 97

Power / Range / Speed

152 HP / 3,500 yards (3,200 m) / 40-42
knots

Propulsion

Kerosene-oxygen wet-heater

Wander Left or Right (max)

45 yards @ 3,500 yards (40 m @ 3,200 m)

Notes: Designed for
Midget Submarines. Also known as the Type 97 Special. Worked
on air enriched to 38% oxygen and bore the same relationship to the Type
97 as did the Type 96 did to the Type 95. Called the Type 98 to fill
a gap in the series, a total of about 130 were produced. Used operationally
during the attack at Sydney, Australia on 31 May 1942.

Notes: A modification
of the aerial Type 91 Mod 3 with a larger air vessel and a different read
buoyancy chamber. Engine was an dual-row, eight-cylinder radial.
About 800 were made between 1943 and 1945. In addition, there was
a Type 2 Special of which about 100 were manufactured in 1944. This
had the same explosive charge but the smaller air vessel of the Type 91.

.

45 cm (17.7") Type 4
(1944) Mark 2

.

Ship Class Used On

Aircraft

Date Of Design

1944

Date In Service

1945

Weight

2,169 lbs. (984 kg)

Overall Length

208 in (5.275 m)

Negative Buoyancy

690 lbs. (313 kg)

Explosive Charge

670 lbs. (313 kg) Type 97

Power / Range / Speed

140 HP / 1,640 yards (1,500 m) / 41-43
knots

Propulsion

Kerosene-oxygen wet-heater

Wander Right or Left (max)

N/A

Notes: A further modification
of the Type 91 Mod 3 Strong. This version was strengthened to permit
a launch speed of 400 knots. The design was greatly simplified for
easier production including the replacement of many steel parts by bronze.
Also note that the designation system for modifications changed from "Mod"
to "Mark" with this torpedo.

.

45 cm (17.7") Type 4
(1944) Mark 4

.

Ship Class Used On

Aircraft

Date Of Design

1945

Date In Service

1945

Weight

2,434 lbs. (1,104 kg)

Overall Length

225 in (5.715 m)

Negative Buoyancy

N/A

Explosive Charge

919 lbs. (417 kg) Type 97

Power / Range / Speed

140 HP / 1,640 yards (1,500 m) / 40-42
knots

Propulsion

Kerosene-oxygen wet-heater

Wander Left or Right (max)

N/A

Notes: Similar to the
previous Type 4 Mod 2 with a larger warhead. Later versions had a
more pointed head, as noted for the earlier Models. This gave an
extra two knots in speed, as shown in the table above.

.

53.3
cm (21") Torpedoes

.

53.3 cm (21") Type 92
(1932) Mod 1 and Mod 2

.

Ship Class Used On

Submarines

Date Of Design

1932

Date In Service

1934 (1942 quantity production)

Weight

3,792 lbs. (1,720 kg)

Overall Length

281 in (7.150 m)

Negative Buoyancy

551 lbs. (300 kg)

Explosive Charge

661 lbs. (300 kg) Type 97

Power / Range / Speed

95 HP / 7,650 yards (7,000 m) / 28-30
knots

Propulsion

Lead-acid electric batteries

Wander Left or Right (max)

130 yards @ 7,650 yards (120 m @ 7,000
m)

Notes: The design of
this torpedo was inspired by the German Navy's successful one of World
War I. Work started in 1921 and in 1925 workable models were produced.
Design work continued and the Type 92 Mod 1 was ready for production in
1934. As there was no need for this torpedo at that time, the design
was set aside. In 1942 production started to supplement the Type
95 torpedoes. The Type 92 was slower than the Type 95 but had even
less track and was easier to produce. The Type 92 Mod 2 was to have
been based upon the German G7e and ten of these torpedoes were delivered
to Japan in 1942. However, a lack of manpower killed this project.
Homing gear based upon the comparison of sound intensity was studied for
this torpedo, but it appears that the torpedo itself was too noisy for
this to be successful.

.

53.3 cm (21") Type 94
(1934) Model 1

.

Notes: Model 1 was an experimental
aircraft torpedo using a kerosene, oxygen and sea water propulsion mixture
that was apparently never made. Reliable details are lacking.

Notes: A slightly improved
version, trading a shorter range for a much larger explosive charge.
As per the Type 93, later versions had a more pointed head, giving a similar
two knot increase in speed, as shown in the table above.

.

53.3 cm (21") Type 96
(1936 but actually 1941)

.

Ship Class Used On

Submarines

Date Of Design

1941

Date In Service

1942

Weight

3,814 lbs. (1,730 kg)

Overall Length

354 in (9.000 m)

Negative Buoyancy

705 lbs. (320 kg)

Explosive Charge

1,213 lbs. (550 kg) Type 97

Power / Range / Speed

400 HP / 4,900 yards (4,500 m) / 48-50
knots

Propulsion

Kerosene-oxygen wet-heater

Wander Left or Right (max)

76 yards @ 4,900 yards (70 m @ 4,500 m)

Notes: This was a modified
Type 95 Mod 1 torpedo developed because of troubles with the "first air
vessel" in the former. Type 96 used 36% oxygen rather than pure oxygen
to reduce starting problems. This also allowed a thin coating of
lubricating oil to be used on valves where as with pure oxygen they had
to be completely oil free which caused corrosion and irregular functioning.
The title of "Type 96" seems to have been given to fill a gap in the series.
As per the Type 93, later versions had a more pointed head, giving a similar
two knot increase in speed, as shown in the table above.

Notes: Model 1 was the
prototype version of the famous "Long Lance" torpedoes. The first
production version was Model 1 Mod 1. This differed by having stronger
ribs in the fore body, the strength of the rear buoyancy chamber was increased,
more cooling water was supplied to the piston rods to prevent overheating
and cracking, and the slide valve gearing was improved.

Mod 2 dated from 1936 and differed in many
areas. The oxygen vessel was made of a deep pressing with one integral
end instead of a hollow forging. This construction was followed in
all subsequent versions. The bracing ribs of the rear buoyancy chamber
were further strengthened and cooling water to the slide valves was increased
together with modifications to the buffer chamber, lubrication of the cross-head
and group valve gearing.

Mod 3 was designed in 1944 and production
started in 1945, but it did not enter service. This mod combined
the oxygen vessel and warhead of Mod 1 with the propulsion system of Model
3, described below.

Earlier versions of these torpedoes may
be distinguished by their round-nosed heads. Later versions had a
more pointed head, developed as a result of tests upon Italian 50 knot
torpedoes (probably the 53.3 cm W 270/533.4 x 7.2
Veloce). This gave an extra two knots in speed, as shown in the
table above.

.

61 cm (24") Type 93
(1933) Model 2

.

Notes: Model 2 was an experimental
type designed in 1935 to meet a staff requirement for a higher speed torpedo
for destroyers. Only two were built and experiments were discontinued
until 1941. In that year, two new engine designs were produced, both
essentially modifications of the two-cylinder double-acting Whitehead type.
In the first engine, the cylinder bore was increased and the prototype
with this engine achieved speeds of 51 knots. The second engine had
thicker cylinder walls and heads and stronger piston rods. This engine
developed pressures of 650 lbs./in2 (45 kg/cm2) and
850 HP. The head of the torpedo was made to a finer, more streamlined
design based upon Italian torpedoes, as noted above. The propeller
pitch was reduced and the RPMs increased. This prototype made three
runs at 56 knots over a 5,500 yard (5,000 m) course. This design
was not further pursued and did not enter service.

Notes: A slightly improved
version, trading a shorter range for a much larger explosive charge.
The first air vessel was replaced by carbon tetrachloride to prevent an
explosion on ignition. Earlier versions of these torpedoes may be
distinguished by their round-nosed heads. Later versions had a more
pointed head, as noted for the earlier Models. This gave an extra
two knots in speed, as shown in the table above.

.

61 cm (24") F3 (Experimental)

.

Ship Class Used On

Ships

Date Of Design

1934

Date In Service

Not in service

Weight

5,952 lbs. (2,700 kg)

Overall Length

336.6 in (8.550 m)

Negative Buoyancy

N/A

Explosive Charge

1,102 lbs. (500 kg) Type 97

Power / Range / Speed

1,000 HP / 8,750 yards (8,000 m) / 60
knots

Propulsion

Kerosene-Oxygen sea-water Turbine

Wander Left or Right (max)

N/A

Notes: Experimental
Turbine powered torpedo. Turbine speed was 17,500 rpm geared down
to 1,650 rpm at the propellers. It was found to be difficult to keep
this torpedo from breaking surface during its runs and development was
halted prior to the start of the Pacific War.

.

Data from"Naval Weapons of World War Two" by John
Campbell"Japanese Cruisers of the Pacific War"
by Eric Lacroix and Linton Wells II
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